The diffeences between web-minning and data-mining were introduced in this paper firstly, then the necessity of Web crawler during web-minning and the development of modern web-minning technology were analysed. Based on the deep understanding of the principle and its function of Web crawler, a minning model popular in modern website was put forward, and a web crawler was designed by the use of this model. Tested by several examples, this kind of crawler can get more diversified pagedata efficiently.